Air heater



Dec. 3, 1929.

I. L. LANGVAND 1,737,970

AIR HEATER Filed Feb. 2. 1926 6 Sheets-Sheet 1 a INVENTOR BY W ATTORNEYS Dec. 3, 1929. I, LANGVAND 1,737,970

AIR HEATER Filed-Feb. 2. 1926 3 Sheets-Sheet 2 Cases Cir/m INVENTOR MM ATTORNEYS Dec. 3, 1929. I. L. LANGVAND 1,737,970

AIR HEATER Filed Feb. 2. 1926 3 Sheets-Sheet 5 cfy j/y /nvmlvrole 7X ATTORNEYS Patented Dec. 3, 1929 UNITED STATES PATENT OFFICE IVAR L. LANGVAND,

COMPANY, OF BAYONNE, NEW

Am HEATER Application filed February My present invention relates to apparatus for transferring heat from one fluid to another, such as is commonly used for heating air by hot flue gases and which for conven- 6 ience, I will term an air heater, though it will be understood that my invention may be used in connection with any apparatus for heat transfer between fluids.

My invention will be best understood from the following description and the annexed drawings, in whichvFig. 1 is a section of an illustrative embodiment of an air heater, such section being taken on the line 11 of Fig. 2; Fig. 2 is a central sectional elevation of the 5 illustrative air heater on a somewhat larger scale than Fig. 1; Fig. 3 is an enlarged section of a portion of one of the tube sheets of Fig. 2, with the tubes broken off; Fig. 4 is a section on the line 4-4 of Fig. 3 and Fig.

5 is a section on a smaller scale of Fig. 3 on the line 5-5.

Like reference characters indicate like parts in the different views.

In the illustrative embodiment, a vertical flue is formed of the tube sheets 10 and 11 and the side walls 12 and 13, the hot gases entering the bottom of this flue and flowing upwardly. Tubes 14, to be described more particularly hereinafter, extend between the tube sheets 10 and 11 with their ends expanded therein, and ducts are arranged over the ends of these tubes so that the air entering through the air inlet 15 will flow first through the upper bank of tubes 14, thence downwardly in the duct 16 and again across the flue through the middle bank of tubes 14 and then downwardly through the duct 17 and through the lower bank of tubes 14 to the air outlet 18. The ducts 16 and 17 are formed respectively between the tube sheets 10 and the outer casing 19 and the tube sheets 11 and the outer casing 20. Plates 21 and 22 divide respectively the air inlet 15 and the air outlet 18 from the ducts 17 and 16.

In order to provide the maximum effective surface of the tubes with the gases flowing upwardly through the flue, I flatten each of the tubes 14, so that they have a section for substantially their entire length with two par- 50 allel long sides 22 connected by short, curved 2, 1926. Serial 110 85348.

surfaces, such as a semi-circle 23. In other words, the tubes are flattened to give a generally elliptical shape, it being understood that by theterm elliptical, I-mean any shape which has a major and a minor axis, but. not necessarily a geometrical elli se. The tubes are positioned in the flue so tiat their long sides or the major axis of the ellipse extends in the direction of gasflow through the tubes, which, in the illustrative embodiment, will be vertical.

In order to make a tight joint between the tube sheets and the ends of the tubes, the ends may be round and expanded into the tube sheet in the usual manner. This, however, is

not as convenient as the arrangement I have illustrated, in which the tubes are first made, throughout their length, of the same flattened cross-section. I provide tube openings in the tube sheets of the same general shape as the cross-section of the tube but somewhat wider as at 25, as best shown in Fig. 4. The tube end is expanded into this opening, as, for instance, by driving in a wedge. By having the opening wider between its ends than the tube section at such points, I obtain a tighter joint than I otherwise would.

By this arrangement, I provide a tubular air heater in which the main body of the tubes can be shaped most advantageously for heating purposes and, at the same time, may be expanded in the tube sheets to provide a tight joint.

It will be understood that certain features of my invention may be used independently of other features and that the embodiment of my invention may be widely varied.

I claim:

1. In a heat exchange device, a tube sheet having a tube opening therein and a tube having its end expanded into said opening, the body portion of the tube having a cross-section formed of a pair of substantially parallel long sides connected at their ends by curved portions and said opening having a cross-section similar to that of the body of the tube but with its long sides wider apart at their centers than'at their ends.

2. In a heat exchange device, a tube sheet having a plurality of tube openings therein,

or BARBERTON, OHIO, ASSIGNOR 110 THE BABGOCK & wILcox JERSEY, A CORPORATION or NEW JERSEY 1 and a tube for each of said openings, each of said tubes being generally elliptical in crosssection and each of said openings being generally of the same cross-section as the body portion of the tube with at least one ameters reater than the corresponding diameter of the section of the body portion of the tube, and the end of the tube being expanded to fit the periphery of the opening;

'3. In a heat exchange device, a tube sheet having a plurality and a tube for each of said openings, eachof said tubes being generally elliptical in cross section and each of said openings being generally of the same cross-section as the body' portion of the tube with its minor axis longer than the minor axis of the cross-section of said body portion, and the end of the tube being expanded to fit the periphery of the I opening.

4. In a heat exchange device, a tube sheet having a tube opening therein, a tube having its body portion of a generally elliptical cross-section and having its end expanded into said openin s, the ratio of the minor axis to the ma or sums of the body portion being less than the ratio of the corresponding axes of the expanded end.

IVAR L. LAN GVAND.

of its diof tube openings therein, 

